no connection to isp

What would cause an USB Epson Scanner to cause no connection to an ISP?

Elaboration:
After troubleshooting onsite this PC, I took it back to my office and re-installed the OS (WIN98). I was able to connect to AOL with no problem. Took it back to the customer, tried to logon,no connection. The modem dails out, you hear the handshaking and thats it. Like it is stuck in a loop trying to hanshake w/ the ISP. Noisy Phone line you might be wondering! Wrong! Phone company verified. Phone technician was onsite to check the next day. To make a long story short. The customer unplugged the EPSON scanner from the USB port and they were able to log on with no problem. Any answer on this one?